As one of wire electric discharge machining methods, there is a method of machining a workpiece (a work), which is a conductive material, along a machining route from a machining start point to a machining end point to separate the workpiece into a part on a side to be left and a part on a side to be cut off (a product part). In this method, an uncut portion is provided to prevent the product part from being cut off in first machining. Thereafter, in second machining, after the original portion of the workpiece and the product part are bridged by a conductive member (a bridging member), the uncut portion is machined.
For example, in a wire electric discharge machining method described in Patent Literature 1, after portions other than an uncut portion are machined, a melting coagulation fixing material is poured into a machining groove in a melted state. The uncut portion, which is an un-machined portion, is machined to separate a workpiece into at least two parts.
In a wire electric discharge machining method described in Patent Literature 2, a bridging member is provided over a product part (a core) and a workpiece. After the core is held by the bridging member, machining of an uncut portion is performed. At this point, finishing is performed after leaving the uncut portion. Thereafter, the bridging member is bridged to a machined portion by a bridging apparatus. The uncut portion, which is an un-machined portion, is machined. At this point, machining up to finishing is performed on the un-machined portion.